[Clinical pharmacology of the selective COX-2 inhibitors]

Cellular membranes function as a storage compartment for celecoxib

Celecoxib is a selective cyclooxygenase-2-(COX-2)-inhibitor used to treat inflammation and pain and prevents colorectal cancer in patients at high doses by affecting several non-COX-2 proteins. However, celecoxib concentrations appropriate to inhibit proliferation or to induce apoptosis in cell culture (up to 100 microM) clearly exceed those in human plasma (up to 10 microM). Therefore, we speculated that celecoxib might accumulate in human cells, which may facilitate the drug's interaction with non-COX-2 proteins. Determination of intracellular celecoxib concentrations by liquid chromatography tandem mass spectrometry gave five- to tenfold higher levels as compared to other coxibs (etoricoxib, valdecoxib, lumiracoxib, and rofecoxib) in different tumor cell types, including human HCA-7 and HCT-116 colon carcinoma cells, BL-41 B lymphocytes, Mono Mac 6 monocytes, and in mouse NIH-3T3 non-tumor fibroblasts. This intracellular accumulation of celecoxib was due to an integration of the drug into cellular phospholipid membranes as demonstrated by nuclear Overhauser spectroscopy/nuclear magnetic resonance. Consequently, celecoxib disturbed the plasma membrane integrity of HCT-116 cells and displayed an increased COX-2-inhibitory potency in HCA-7 cells. The use of other coxibs demonstrated that intracellular accumulation is peculiar of celecoxib. Accumulation of celecoxib in human cells may provide a novel molecular basis for the ability of the drug to interact with non-COX-2 targets in vivo despite comparatively low plasma concentrations.

Effects of parecoxib and dipyrone on platelet aggregation in patients undergoing meniscectomy: a double-blind, randomized, parallel-group study

BACKGROUND

Based on a PubMed search of the literature using the terms parecoxib, platelets, thromboxane, bleeding, and platelet aggregation, the effects of parecoxib on platelet function have not fully been established under clinical conditions.

OBJECTIVE

The aim of this study was to determine platelet aggregation, thromboxane B(2) (TxB(2)) formation, and plasma concentrations with the use of parecoxib in postoperative pain management.

METHODS

This double-blind, randomized, parallel-group trial was conducted at the University Hospital for Orthopedic Surgery, Friedrichsheim, Frankfurt, Germany. Male and female patients aged 18 to 55 years and scheduled to undergo routine partial meniscectomy (or a similar arthroscopic procedure) were eligible. All patients received dose-adjusted enoxaparin before surgery and parecoxib 40 mg BID or dipyrone 1000 mg QID. Blood samples were drawn before first injection (predose) and at 0.5, 2, and 6 hours after injection. Platelet aggregation (expressed as percentage of the maximal light transmittance [A(max)]) was induced with arachidonic acid (A(max)AA) and collagen (A(max)CO). TxB(2) formation was determined using enzyme-linked immunosorbent assay.

RESULTS

This study included 26 patients. In both treatment groups, 8 males and 5 females, all white, were enrolled. In the dipyrone group, the mean age was 48 years (range, 32-61 years) and the mean weight was 85 kg (range, 63-122 kg); in the parecoxib group, the mean age was 47 years (range, 31-61 years) and the mean weight was 81 kg (range, 57-100 kg). Median (interquartile range [IQR]) predose values for A(max)AA were 76% (65%-83%) in the parecoxib group and 87% (80%-89%) in the dipyrone group. At 0.5 hour after injection, A(max)AA was 52% (5%-77%) with parecoxib and 8% (0%-11%) with dipyrone (P=0.004). At 2 hours after injection, A(max)AA was 78% (72%-80%) in the parecoxib group versus 7% (5%-11%) in the dipyrone group (P<0.001). At 6 hours after study drug administration, no treatment differences were found. For A(max)CO, no statistically significant differences were found. Consistent with the stronger inhibition of aggregation, patients who received dipyrone had lower TxB(2) formation values. Six hours after parecoxib administration, mean TxB(2) formation was significantly enhanced compared with predose values (132 ng/mL [IQR, 62-228 ng/mL] vs 185 ng/mL [IQR, 135-239 ng/mL]; P=0.05).

CONCLUSIONS

Platelet aggregation and TxB(2) formation were significantly lower for 6 hours in dipyronetreated patients compared with parecoxib-treated patients. In contrast, TxB(2) formation was increased with parecoxib 6 hours after administration compared with pretreatment values. In this small study, parecoxib did not affect platelet aggregation in a population of patients undergoing routine partial meniscectomy (or a similar arthroscopic procedure) under clinical conditions.

Analgesie in der Kolonchirurgie

BACKGROUND

The goal of our study was to evaluate the morphine-sparing effect of nonsteroidal anti-inflammatory drugs (NSAIDs) following both conventional and laparoscopic colon surgery.

MATERIALS AND METHODS

In this prospective, randomized clinical trial, 180 patients were assigned to three groups. Two groups received either paracetamol or parecoxib/valdecoxib in addition to piritramid via patient-controlled or nurse-controlled analgesia pump. Patients in the control group received piritramid only. The total piritramid consumption during hospital stay was recorded.

RESULTS

Total opioid consumption was significantly lower in the two groups who received NSAIDs. Comparing conventional and laparoscopic surgery, the latter group had much lower opioid consumption.

CONCLUSION

The use of NSAIDs following colon surgery significantly reduces postoperative opioid consumption.